Percussion or repercussion apparatus



Jufie 4, 1940.

v F. L. DOUGLAS PERCUSSION 0R REPERCUSSION APPARATUS Filed April 12, 1938 Patented June 4, 1940 U-NlTED STATES PATENT I OFFICE PERCUSSION 0R REPERCUSSION APPARATUS Frank Leslie Douglas,

Bournemouth, England 4 Claims.

This invention relates to improvements in or relating to percussion or repercussion apparatus, for example rammers, pummers, pile-drivers and the like, apparatus of this kind hereinafter referred to for convenience as percussion apparatus, being used for instance for driving piles, for consolidating earth, road-making material, and for breaking up concrete and the like.

It has already been proposed to provide Diesel operated percussion apparatus, but the known proposals have been open to objection, inter alia, on the grounds of complexity and relatively low degrees of efiiciency and reliability.

One of the objects of the present invention is to provide Diesel operated percussion apparatus which is of simple construction and very reliable and eflicient in operation.

According to the present invention I provide percussion apparatus operating on the Diesel principle and comprising a cylinder and a piston wherein provision is made for compressing the air or other gasforming the charge or part of the charge prior to admission to a combustion chamber.

With this construction valves are dispensed with the cylinder being ported to provide air inlet and exhaust ports which are controlled by the relative movement of the cylinder and piston, the cylinder on each side of the piston constituting respectively combustion and compression chambers, which are placed in communication by a passage at certain positions of the piston, to permit of feeding ofv the whole or part of the air charge from the compression cylinder to the combustion chamber thereof. The charge of air is compressed in the combustion chamber and liquid or vaporised fuel, for example, oil, injected thereinto, the compression ratio being such that ignition automatically results.

Preferably the oil injection pump is operated by mechanism controlled by the relative movements of the cylinder and piston.

The compression chamber which is located below the piston, is so arranged that relative movement of the cylinder and piston in one direction causes an increase in the volume of such chamber and in the other direction causes a decrease in such volume, the former movement eflecting induction of a charge or induction of part of a charge into the combustion chamber and the latter efiecting compression thereof and transfer to the combustion chamber through the passage aforesaid.

The piston or cylinder may be adapted to serve as the operative part of the apparatus 1. e., the

part which, strikes the material or object to be driven, consolidated or broken although, in general, I prefer to provide a foot formed integrally with or attached to a piston rod extending from the piston and having a portion serving as an 5: anvil surface upon which the cylinder strikes at the end of the percussion stroke.

In some cases it is desirable for the cylinder of the apparatus only to reciprocate, Whereas in I other cases it is desirable for there to be some 10 reciprocation of the piston as well. In the latter cases upward movement of the piston may be brought about directly by fluid compression below the piston and/or by means of one or more springs or like resilient interconnecting means 15 provided between said cylinder and piston. Starting of the apparatus is eifected by mechanigoal reciprocation of the cylinder or by effecting reciprocation with the aid of compressed air.

In order that the invention may be understood 20 reference is directed to the accompanying drawing wherein:

Fig. 1 is a sectional side elevation of a percussion apparatus constructed according to the invention; 25

Fig. 2 is an elevation at right angles to Fig. l; and

Fig. 3 is a section on the line 3-3 of Fig. 1 showing the relative positions of certain ports provided in the cylinder. 80,

The example of the apparatus illustrated in the drawing includes a piston having a piston rod 2, tothe lower end of which is fitted a foot 3 adapted to rest on the object or material to be driven, consolidated or broken. The pistonis 35 enclosed by a cylinder, the lower end of which conforms with the upper surface of said foot and upon which it normally rests, the cylinder at this part slidably embracing the aforesaid piston rod 2 and forming a gas-tight joint therewith. The 0 cylinder comprises a compression chamber 5 and a combustion chamber 6.

The upper surface of the piston may be provided with any suitable deflector or the like, similar for example to those used in two-cycle internal combustion engines, in order to promote an eflicient scavenging action.

One or more longitudinal passages (two being shown in the drawing) are provided in the wall of the aforesaid cylinder, and each passage 5o opens at each end into the cylinder to provide ports, one indicated by the reference 8 located near the lower limit of the aforesaid compression chamber and forming an outlet from the compression chamber 5 and the other indicated IQ by the reference 9 forming an inlet to the combustion chamber. Said two ports may be interconnected, for example, by means of an external conduit or pipe or by means of the passage I cored in the cylinder wall. The ports 8 and 9 and the passage I or conduit serve to transfer air or gas from the compression chamber 5 to the combustion chamber 6 pursuant to relative movement of the cylinder and piston.

One or more further ports ill are provided in the aforesaid cylinder, two being shown in the drawing, such further port or ports serving as an outlet for exhaust gases and being located substantially in alignment with, but diametrically opposite to, the aforesaid upper transfer port or ports 9. Any suitable silencer, exhaust system or the like may, of course, be associated with said exhaust port or ports.

The cylinder 4 has a removable head II fitted with an oil injection nozzle I2 of known con struction which is supplied periodically with a charge of oil by means of a pump I3 through a conduit I4, the pump receiving oil from a reservoir I5 conveniently mounted on the cylinder head II and supplying oil to the pump I3 by way of a pipe 16. every complete downward movement of the cylinder 4, relatively to the piston l by means of a tappet rod I'I, slidably mounted in bearings I8, the upper one of which supports the pump I3, provided on the wall of the cylinder. The tappet rod I'I co-operates with a pivoted abutment I9 fitted to the foot 3 so that when the cylinder and piston close together as shown in the drawing the tappet rod IT is moved to actuate the pump I3 whereby a charge of oil is injected into the combustion space 6. The abutment I9 may be rocked on its pivot 29 by an arm 2| to the position shown in dotted lines in Figure 2 to render the apparatus inoperative.

The operation of the device is as follows:-

With the parts in their normal position of rest, i. e., the cylinder at the botom of its stroke and resting on the foot 3, the apparatus is started by forming and firing a charge in the combustion chamber 6 whereupon the cylinder moves to the top of its stroke so compressing the gas or air in the compression chamber 5 which previously entered through the ports Iii and transferring it by passage l to the combustion chamber 6 as soon as the upper transfer ports 9 are uncovered. At the same time as the transfer ports are opened the exhaust ports I 0 are also opened to the atmosphere so that expanded gases escape and there is a scavenging action by the incoming charge.

At the end of the up-stro-ke the cylinder falls so effecting the desired percussion stroke when it strikes the foot 3, and, at the same time compresses the air or gas in the combustion chamber 6 in readiness to receive the charge of oil from the nozzle I2 upon the completion of the downward movement of the cylinder which actuates the pump 13 through the tappet I'I striking the abutment I9. The action continues until the pump I3 is rendered inoperative by displacement of the abutment I9.

An important feature of the above described embodiment of the invention resides in the fact that there are no exhaust or inlet valves which are liable in practice to cause many troubles due, for instance, to burning or sticking of the valves or to breakage or loss of temper of the actuating springs, a further important feature resides in the fact that the use of a falling or loose piston,

employed in percussion apparatus at present on The pump is actuated once upon the market, is entirely avoided, which features, in combination with others apparent from the foregoing specification result in the apparatus being of greatly increased reliability and efficiency as compared with known forms of apparatus. It is further apparent that very few working parts are necessitated and the overall length of the apparatus can be materially less than that of known percussion apparatus.

Whilst I have hereinbefore described some embodiments of my invention I wish it to be under stood that the specific details may be varied without departing from the scope of such invention. Thus, for instance, there may be many modificatons in the arrangement of ports, passages or the like for inducing and transferring a charge to the combustion chamber and effecting exhaust of the burnt gases. Moreover, the fuel reservoir may be adapted to contain any suitable fuel and the apparatus may be made of any desired dimensions and weight.

What I claim and desire to secure by Letters foot member fixed to the outer end of said piston rod and adapted to receive the impact from-said cylinder and transmit it to a driven member, said cylinder having a port aiiording. communicw tion between the interior of said combustion chamber and air outside the cylinder, and the device also having a duct affording communication between said chambers, the said duct and port being controlled by the relative movement of the said cylinder and piston, and the said duct being closed by the piston during part of .the combustion stroke of the device whereby to permit compression of gas in. said compression chamber during said part of the combustion stroke and being uncovered by said piston during a later part of said combustion stroke whereby to permit the compressed gases in the compression chamber to pass into the combustion chamber to assist in scavengingthe latter chamber and to form a substantial part of a new combustion charge. I

2. A Diesel power hammer comprising a reciprocating cylinder constituting an impact member, a piston dividing said cylinder into a combustion chamber locatedtoward one end of said cylinder and a compression chamber located toward the other end thereof, a piston rod fixed to said piston and extending through the compression chamber end of said cylinder, anda foot member fixed to the outer end of. said piston rod and adapted to receive the impact from said cylinder and transmitit to a .driven member, said cylinder having a port affording communication between the interior of said combustion chamber and air outside the cylinder, and said cylinder also having a passage in the wall thereof aiiord-ing communication between said chambers, the said passage and port being controlled by the relative movement of the cylinder and piston, I

stantially uniform diameter throughout the length thereof, a piston, similarly of substantially uniform diameter, dividing said cylinder into a combustion chamber located toward one end of said cylinder and a compression chamber located toward the other end thereof, a piston rod fixed to said piston and extending through the compression chamber end of said cylinder, and a foot member fixed to the outer end of said piston rod and adapted to receive the impact from said cylinder and transmit it to a driven member, said cylinder having a port affording communication between the interior of said combustion chamber and air outside the cylinder, and said cylinder also having a passage in the wall thereof afiording communication between said chambers, the

said passage and port being controlled by the relative movement of the cylinder and piston, and the said passage opening into said combustion chamber at a point beyond which the piston may continue to move to a considerable extent during the combustion stroke of the de" vice whereby to leave said passage open and to force gas from said compression chamber through said passage and into said combustion chamber during a substantial part of the said combustion stroke.

4. A Diesel power hammer according to claim 3, further characterized in that said port is disposed directly opposite to the opening of said passage into the combustion chamber and in that the length of the piston, the length of the interior of the cylinder and the disposition of said port and the oppositely disposed opening of said passage are such that the piston may travel substantially beyond said port and passage opening in its movement in both directions relatively to the said cylinder. I

FRANK LESLIE DOUGLAS. 

